The present invention relates to a baby trailer and more specifically, to a retractable frame structure for baby trailer, which comprises a rigid base frame, a bottom frame bar horizontally slidably mounted in the base frame and selectively lockable in the extended or received position, a backrest, and a top frame bar vertically slidably mounted in the backrest and selectively lockable in the extended or received position.
U.S. Pat. Nos. 7,341,265 and 8,444,173 disclose a baby trailer that allows adjustment of the bottom frame bar between an extended position and a received position. However, because the seat supported on the bottom frame bar is a flexible fabric material, it will be forced to curve downwards when a baby or child sits thereof, causing the baby or child to feel uncomfortable. When the baby trailer is moved over a large stone or any other external object on the road, the downwardly curved seat can hit the external object, leading to an injury accident. In order to assure a high level of stability and sitting comfort, the seat is preferably made of a rigid or hard material and attached with a soft or flexible pad or covering. Further, the frame structures of conventional baby trailers are not highly retractable or collapsible to save the storage space. In consequence, conventional baby trailers are not conveniently for packaging, delivery or storage.
The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a retractable frame structure for baby trailer, which is highly retractable to reduce the storage space, saving the packaging and delivery costs. It is another object of the present invention to provide a retractable frame structure for baby trailer, which assures a high level of sitting comfort and moving safety and operational convenience.
To achieve these and other objects of the present invention, a retractable frame structure for baby trailer comprises a rigid base frame, a bottom frame bar horizontally movable in and out of a front side of the rigid bottom, first lock means for selectively locking the bottom frame bar to the base frame in the extended or received position, a backrest, a top frame bar vertically movable in and out of a top side of the backrest, and a second lock means for selectively locking the top frame bar to the backrest in the extended or received position.